My feeling having both an E6600 and a 5600+ is that these two chips are comparable. Which means that you'd need a 2.8 Ghz Turion to match a 2.4 Ghz Core 2. AMD is shipping 2.4 but I checked Hp and Dell recently and HP offers the 2.2 Ghz Turion X2 max. So I don't see AMD as competitive until they get Barcelona out there. BTW, I don't think they're going to do a 2.8 Ghz notebook chip but it would be fun to play with. Even with one core.
Could AMD pick up another 5%? I guess so. But it would be at the low end where there is a lot of demand but I assume the margins are nothing to shout about.